I have a custom control inherited from RichTextBox. This control has the ability to "disable" rich text editing. I achive this by just setting the Rtf property to the text property during the TextChanged event.

this is how my code looks like:

        private bool lockTextChanged;
        void RichTextBox_TextChanged(object sender, EventArgs e)
        {
            // prevent StackOverflowException
            if (lockTextChanged) return;

            // remember current position
            int rtbstart = rtb.SelectionStart;
            int len = rtb.SelectionLength;


            // prevent painting                
            rtb.SuspendLayout();

            // set the text property to remove the entire formatting.
            lockTextChanged = true;
            rtb.Text = rtb.Text;
            rtb.Select(rtbstart, len);
            lockTextChanged = false;

            rtb.ResumeLayout(true);
      }

That worked well. However in a large text with like 200 lines the controls jitters (you see the first lines of text for the wink).

To prevent that from happening I filter the WM_PAINT between SuspendLayout() and ResumeLayout()

    private bool layoutSuspended;
    public new void SuspendLayout()
    {
        layoutSuspended = true;
        base.SuspendLayout();
    }

    public new void ResumeLayout()
    {
        layoutSuspended = false;
        base.ResumeLayout();
    }

    public new void ResumeLayout(bool performLayout)
    {
        layoutSuspended = false;
        base.ResumeLayout(performLayout);
    }

    private const int WM_PAINT = 0x000F;
    protected override void WndProc(ref System.Windows.Forms.Message m)
    {
        if (!(m.Msg == WM_PAINT && layoutSuspended))
            base.WndProc(ref m);

    }

that did the trick, the RichTextBox isn't jittering anymoe.
That's what I wanted to achive, except one thing:
The scrollbar is still jittering everytime I type text to my control.

Now my question: Does anyone have a clue for me how to prevent the scrollbar from redrawing during Suspend/Resume Layout?